In the CASE environment, automated systems production has traditionally been based on a methodology which examines the current physical process in order to determine new system requirements. Such automated systems production based on a process-oriented methodology often results in awkard key structures and access paths, highly unnormalized physical data structures, and programs that are burdened with navigating and updating those data structures.
When pre-defined data structures are available for process development, they are usually a physical data implementation, built to satisfy the data needs of one or more specific processes. These designs are also somewhat constrained by the idiosyncrasies of a particular access method. Also, they are typically based upon physical data implementations to which the system designers were exposed in the past.
Such constraints can unduly impact the design of screens, reports and other batch processing. Close ties between processes and physical data structures can make a system difficult to construct and maintain. Further disadvantages are excessively complex data structures and access paths which can result when performance issues are over-emphasized early in a development effort.